The objective of the proposed research is to discover ways by which drugs can be employed to regulate or alter the release of oxytocin from the neurohypophysis. It is hoped that the studies will provide a basis for the development of drugs useful for the treatment of problems associated with labor, especially premature labor. The release of oxytocin and neurophysin(s) from the isolated hypothalamoneurohypophysial system by various drugs will be investigated using rats under a variety of physiologic states. The possible release of oxytocin from various pools will be evaluated. Changes in the oxytocin and neurophysin content of fetal pituitary glands will be studied to determine their contribution to labor. The basis for developing a high pressure liquid chromatography method for the separation and detection of nanogram quantities of oxytocin and vasopressin is considered. Experiments are also proposed for the study of an oxytocin derivative.